The use of magnetic disks for data storage has become widespread in the computer industry (U.S. Pat. No. 4,535,374). Data can be stored on both sides of a magnetic disk in concentric circular recording tracks. To translate data to and from a spinning disk during read/write operations, at least one magnetic transducer is situated within micrometers of a surface of the disk. To accommodate such positioning, the transducer is affixed to a specially designed platform. The platform is aerodynamically designed to fly on a thin cushion of ambulant air adjacent to the recording surface that is created by the spinning disk. The air cushion serves to define the clearance between the communicating faces of the transducer/platform combination, hereinafter referred to as a head, and spinning disk.
Each head in a magnetic disk storage system is supportably connected to a flexure. The flexure allows the head to pitch and roll relative to the associated disks spinning surface, so that a substantially parallel relationship between the communicating faces of the head and disk can be maintained during read/write operations. Such parallel relationship contributes to accurate data translation.
Typically, the flexure is supportably connected to the free end of a predominantly flat, cantilevered suspension arm which is attached to a movable carriage adjacent to the associated disk. To radially access the plurality of concentric recording tracks on a magnetic disk, the carriage is oriented so as to move along a horizontal axis that coincides with a radial line extending from the center of the associated disk. Since the position of the carriage relative to the disk is electrically controllable, the head, which is operatively associated with the carriage, can be radially positioned to read from and write onto each of the concentric recording tracks.
The suspension arm, or a component member thereof, is spring-loaded in a conventional manner to provide a vertical loading force on the head so as to urge the head towards the associated disk, and counterbalance the air bearing force associated with the afore-mentioned cushion of ambulant air. In this manner, the desired head/disk clearance can be maintained during read/write operations as variations in the disk surface are encountered. Maintenance of a near constant head/disk clearance, and substantially parallel relationship between the head and disk as previously discussed, is necessary to ensure accurate data translation and minimal head/disk destructive contact. It should be emphasized that the density of data stored on a magnetic disk, and the signal-to-noise ratio established during data translation, can be increased as the head/disk clearance constant is decreased. Therefore, it is desirable to maintain as small a clearance constant as possible to maximize both the accuracy of data translation and the data storage capabilities of a computer system. The smallest head/disk clearance constant found in a commercially available disk drive system is realized through the employment of a unique head/flexure/suspension arm combination, as illustrated and described in U.S. Pat. No. 4,167,765. That combination is known in the art as Whitney technology. The combination of a Whitney head, flexure and suspension arm is presently employed in the IBM 3370 and 3380 disk drive systems.
An essential disadvantage of the suspension arm presently used in magnetic disk storages is that it is subjected to a special bending process which serves to produce the initial load force. During this process, the predetermined initial load force is coarse-adjusted to be fine-adjusted during head assembly, tested for separation limits and sorted. After the head/suspension assembly (suspension arm, flexure, slider) has been mounted on the arm portion, the initial load force is again measured and adjusted, if required.
The bending process of the suspension arm is rendered particularly elaborate by the fact that in addition to the initial load force, a non-planarity (S-shaped bend) to be accurately defined is imparted to the suspension arm, to ensure particular resonance characteristics. For this purpose, the manufacturer of the suspension has to optimize the desired value of the load force and the non-planarity in the bending range by matrix testing.
A further disadvantage of the head suspensions currently used in magnetic disk storages is that their design is such that they require a clear disk spacing of 8 to 9 mm.
However, as the trend of magnetic data storage technology is from 35.56 cm (14 inch--high-end) to 13.33 or 8.25 cm (5.25 or 3.25 inch--low-end) files, this means technically that it is necessary to increase the number of bits per inch and to reduce the clear magnetic disk spacing. The clear spacing of currently planned "IBM low-end files" is 3.5 mm. This is the spacing available for installing an arm portion with two magnetic head suspensions above each other. Such a clear spacing necessitates a reduction of the overall height of the magnetic head suspension and a slider that can be moved closer to the surface of the magnetic disk. The reduction of the clear disk spacing makes great demands on the design of the magnetic head suspension, since the reduction in the overall height of the magnetic head suspension and the fact that, as a result, the slider has to be moved closer to disk surface, adversely affect the oscillation and flight characteristics of the slider.
Therefore, the design of the magnetic head suspension must be such that the reduction of the overall height of the magnetic head suspension does not adversely affect the oscillation and flight characteristics of the slider and that the magnetic head suspension is easy to produce and to install.
This requirement is not met by the magnetic head suspensions currently used in magnetic disk storages.
German Patent 25 34 205 describes a magnetic head suspension, the spring element of which is provided with a triangular portion, the base of which terminates in a rectangle and the apex of which comprises a framelike square acting as the actual magnetic head suspension.
The triangular portion has raised edges forming a groove in which the flat and equally triangular intermediate piece is fixed, with the bent extension of the latter acting as a support face for the magnetic head.
The framelike square is made up of two horizontally positioned outer frame sections and two outer vertically positioned crosspieces. A tongue, positioned parallel to the frame sections and supporting the slider, extends from the outer frame crosspiece.
Such a magnetic head suspension has a complex design and is difficult to produce and assemble. The slider in particular must be designed such that it may be installed between the tongue and the intermediate piece. This involves very tight production tolerances for the slider and is technically unfavorable, as the slider is the most expensive component of the magnetic head suspension.
IBM Technical Disclosure Bulletin, Vol. 28, No. 6, Nov. 1985, p. 2492, describes a magnetic head suspension consisting of an arm attachment to which ramp plates bent on either side are fixed, with each ramp plate supporting a prebiased suspension arm, on whose free end the slider is mounted.
With this magnetic head suspension, too, it is necessary for the suspension arm to be mounted on the ramp plate in a prebiased state. The ramp plate does not eliminate fine and subsequent adjustment of the suspension arm.
A further difference is that the ramp plate is designed as a separate bent element which is mounted to the arm attachment.
The magnetic head suspension of none of the afore-mentioned prior art material is suitable for obtaining the clear disk spacing of as little as, say, 3.5 mm, as is required by low-end files.